1. Field of the Invention
The present invention relates to a touch operation information output device which outputs coordinate data of a touched position on an operating surface.
2. Description of Related Art
Vehicles, for example, are provided with a conventional display device with a touch operation function. One example of this display device is constructed to detect a touched position with respect to a display screen through an optical sensor. Specifically, light projection elements and light receiving elements are arranged so as to form a plurality of parallel optical axes corresponding to a vertical direction and a horizontal direction of the display screen. Based on an optical axis extending between the light projection element and the light receiving element being severed by touching the display screen with a finger, the display device detects the center position of the touched area and outputs the coordinate data thereof.
Accordingly, when a screen for an air conditioner, for example, is displayed, the air conditioning function in the vehicle can be arbitrarily adjusted by touch-operating a button display portion which is displayed on the screen for the air conditioner. By using this type of display device with a touch operation function, switches for devices on the vehicle, such as the air conditioner, a radio and a car navigation system, can be omitted. Therefore, the instrument panel can look neat.
Incidentally, with the above-mentioned conventional display device having a touch operation function, the driver is required to touch the display device by stretching his arm, thus rendering controllability of the display device insufficient. Therefore, it has been considered to separate the touch operation function from the display device. In other words, a touch operation information output device that outputs coordinate data, which shows the finger-touched position with respect to the operating surface and also outputs the "on" data which shows that the aforementioned operating surface has been press-operated, is provided separately from the display device. The touch operation information output device is installed, for example, on the arm rest of the driver's-side door, and can improve the operability by the driver.
However, there is a disadvantage in that the finger-touched position with respect to the operating surface cannot be recognized when the driver performs the touch operation of the touch operation information output device of this type while driving.